This invention relates to new 4-amino-2-(2 or 3-amino or substituted amino-ethyl or propyl)-phenol compounds and compositions containing these new compounds, as primary intermediates for oxidative coloring of hair fibers.
Coloration of hair is a procedure practiced from antiquity employing a variety of means. In modern times, the method most extensively to color hair is an oxidative dyeing process utilizing one or more oxidative hair coloring agents in combination with one or more oxidizing agents.
Most commonly a peroxy oxidizing agent is used in combination with one or more oxidative hair coloring agents, generally small molecules capable of diffusing into hair and comprising one or more primary intermediates and one or more couplers. In this procedure, a peroxide material, such as hydrogen peroxide, is employed to activate the small molecules of primary intermediates so that they react with couplers to form larger sized compounds in the hair shaft to color the hair in a variety of shades and colors.
A wide variety of primary intermediates and couplers have been employed in such oxidative hair coloring systems and compositions. Among the primary intermediates employed there may be mentioned p-phenylenediamine, p-toluenediamine, p-aminophenol, 4-amino-3-methylphenol, N,N-bis(2-hydroxyethyl)-p-phenylene diamine, 1-(2-hydroxyethyl)-4,5-diaminopyrazole and as couplers there may be mentioned resorcinol, 2-methylresorcinol, 3-aminophenol, 2,4-diaminophenoxyethanol, and 5-amino-2-methylphenol.
There are numerous additional requirements for oxidation dye compounds that are used to dye human hair besides the color or the desired intensity. Thus, the dye compounds must be unobjectionable in regard to toxicological and dermatological properties and must provide the desired hair color with a good light fastness, fastness to a permanent wave treatment, acid fastness and fastness to rubbing. The color of the hair dyed with the dye compounds in each case must be stable for at least 4 to 6 weeks to light, rubbing and chemical agents. Furthermore, an additional requirement is the production of a broad palette of different color shades using different developer and coupler substances. Many of the desired shades have been produced with dyes based on p-aminophenol. However, as indicated in U.S. Pat. No. 4,997,451, the use of p-aminophenol is being questioned, for possible toxicological reasons. The proposed replacements for p-aminophenol have not proved entirely satisfactory. There is therefore a need for new primary intermediate compounds to meet one or more of the desired properties but not possessing the possible toxicological drawbacks possessed by p-aminophenol.
It is therefore an object of this invention to provide new primary intermediate compounds useful in place of p-aminophenol to provide a wide range of different color shades with various combinations of primary intermediates and couplers, but which avoids the drawback of p-aminophenol.
It has been discovered that the new 4-amino-2-(2 or 3-amino or substituted amino-ethyl or propyl)-phenol compounds are suitable primary intermediates for hair coloring compositions and systems for providing good oxidative coloration of hair and for providing acceptable light fastness, fastness to shampooing, good selectivity, fastness to perspiration and permanent wave treatment, and suitable for providing a wide variety of different color shades with various primary intermediate and coupler compounds.
The invention provides new 4-amino-2-(2 or 3-amino or substituted amino-ethyl or propyl)-phenol compounds of formula (1): 
wherein R1 and R2 are each independently selected from hydrogen atoms, a C1 to C5 alkyl or hydroxyalkyl group, or R1 and R2 together with the nitrogen atom to which they are attached form a 5 or 6 member cyclic ring optionally containing one or more additional atoms selected from O, N or S atoms, such as a piperazine, piperidine, imidazole, or morpholine, and n is equal to 1 or 2, with the proviso that when n is equal to 2 only one of R1 and R2 may be hydrogen.
These novel primary intermediates are used to provide coloration to hair in which there is good dye uptake by the hair and provides shades or colors which are stable over a relatively long period of time. The novel primary intermediates provide for dyeing of hair to impart color or shades that possess good wash fastness and do not undergo significant changes on exposure to light or shampooing.
The new 4-amino-2-(2 or 3-amino or substituted amino-ethyl or propyl)-phenol compounds of formula (1) of this invention can be prepared according to the following reaction sequence, where R1 and R2 are as defined hereinbefore: 
In this synthesis procedure nitration of 2-coumaranone or dihydrocoumarin of formula (2) with nitric acid/sulfuric acid produces a compound of formula (3). Reaction of the compound of formula (3) with a reagent of the formula R1R2NH provides a compound of formula (4). Reduction of the compound of formula (4) with borane-THF complex produces a compound of formula (5). Catalytic hydrogenation of the compound of formula (5) with Pd/C under hydrogen produces a compound of formula (1).